The present invention relates to a gas cooled nuclear fission reactor and more particularly to such a reactor using spherical fuel elements featuring inherent safety mechanisms which rely on gravity only.
A need for a low weight, high power density nuclear reactor for electricity generation on ship board has become acute. Since weight and space requirements are important factors for such application and since liquid metal cooled reactors are not attractive for this application due to safety considerations, existing knowledge suggests that a gas cooled reactor will allow operation at highest possible temperatures and so afford achievement of highest possible power densities.
Gas cooled reactors employing spherical fuel elements have been used before for land based operation. These reactors do not, however, use a rotating fuel element container. They do not allow an emergency shut down within seconds, since control rods have to be driven into the heap of spherical fuel elements, which take considerable force and time. The heap of spherical fuel elements are contained in a stationary hour-glass shaped container, in these reactors, which for safe and steady operation could not tolerate the rolling of a ship, since this would cause movement of the spheres in respect to each other, which in turn would change the reactivity of the total system, thus causing fluctuations in power generation or even dangerous power excursions.